Sony introduces longer-lasting, faster-charging batteries for consumer electronics

TechOnline India - August 13, 2009

Sony has announced a new line of olivine-type lithium iron phosphate batteries that promise rapid-charging, higher power, and longer lasting over other battery technologies.

In an attempt to shake out their unfortunate reputation with respect to batteries (Sony battery catches fire; Toshiba 'redoubles' recall efforts), Sony is introducing a new type of lithium ion battery that promises higher power and longer life than the performance of traditional alkaline batteries and lithium ion batteries currently on the market.

Sony's new LiFePO4 battery

This promised performance improvement comes from the use of Olivine-type lithium iron phosphate as the cathode material, the first commercially available battery to use this particular substance. This new cathode material, in combination with Sony's proprietary particle design technology that minimizes electrical resistance to deliver high power output, has created a product that Sony claims has a high power density of 1800W/kg and extended life span of approximately 2,000 charge-discharge cycles. This new technology also takes advantage of cell structure design technology that Sony acquired while developing its "Fortelion series" of lithium ion secondary batteries.

Olivine-type lithium iron phosphate - the material of the future?

First patented in 1996 by Dr. John Goodenough and his team at the University of Texas, Olivine-type lithium iron phosphate (or LiFePO4) was developed as a solution to the low discharge rate and short cycle life that came with other lithium-ion cell structure technologies like lithium cobalt oxide and lithium manganese oxide. As a potential cathode, LiFePO4 is a very stable material that many scientists believe can have numerous consumer applications from rechargeable batteries for products to usage in future iterations of electric vehicles (Chevrolet's upcoming Volt vehicle uses a 220-cell lithium-ion battery). LiFePO4's olivine crystal structure features a crystal lattice deformation that is smaller than other battery structures, resulting in an improved electric discharge process. As a result, the cycle life of LiFePO4 is extremely long and features characteristics that help it withstand oxidation and an acidic environment, gives the battery more electrolyte choice, and the battery performance subsequently is optimized. LiFePO4 technology also demonstrates an excellent shelf life when not in use.

LiFePO4 structure - Source: STL Life Power

Another benefit of LiFePO4 is that it is considered one of the 'safest' battery technologies. The cell structure of LiFePO4 remains stable when placed under extreme high temperatures. It keeps its stability even at temperatures between 300 to 500 degrees Celsius and can even withstand a maximum of 700 degrees Celsius. At these same temperatures, other lithium batteries, such as those made with cobalt, nickel or manganese, begin to disintegrate and can potentially explode under these extreme heat conditions.

Sony takes advantage of LiFePO4 benefits

By utilizing LiFePO4 for their new rechargeable batteries, Sony has been able to introduce a battery to the market that is capable of rapidly charging (99% charge completed in 30 minutes) while maintaining a stable discharge of voltage when in use. Sony also takes advantage of LiFePO4's long-life as their new battery can retain more than 80% of its capacity after 2,000 charge-discharge cycles. This enhanced durability makes their battery an optimal choice for use in mobile and portable electronic devices.

With this product introduction, Sony has created a battery that has positive effects for the environment. A rapid-charging, longer-lasting battery can replace traditional alkaline and lead-based batteries that feature a short life cycle and contain materials that can be toxic to the environment as well as lithium-ion based batteries because of LiFePO4's ability to retain most of its charge even after 2000 charge-discharge cycles. LiFePO4 technology could even find itself as the material of choice for electric vehicles in the near future. The possibilities of a vehicle with a battery that would be able to travel numerous miles before requiring a recharge would garner a lot of interest from car manufacturers looking to compete with GM and their Volt electric car.

The new battery from Sony was first supplied for use in power tools in June of 2009, but will be issued in wide release for use in applications such as motor driven devices and portable electronic products such as mobile phones and netbooks.


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